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Ethoxyl group analysis

In cases where 2D NMR experiments are insufficient for a complete analysis of anionic surfactant mixtures, LC-NMR may provide better information. Characterisation of fatty alcohol ethoxylate (FAE) based oligomeric surfactants by on-line 2D (GCOSY, TOCSY and Homo 2DJ) stopped-flow HPLC- H NMR has been described [655,656]. The analysis of a typical mixture comprising three components (PEG and PEOs with different end-groups) is shown in Figure 7.34. In this representation, the 111 NMR frequency domain is in the... [Pg.521]

Here, the mixture analytical FIA-MS-MS approach reached its limitation to identify compounds. Hence, LC separations prior to MS analysis are essential to separate compounds with the same m/z ratio but with different structures. The behaviour in the LC separation will be influenced by characteristic parameters of the surfactant such as linear or strongly branched alkyl chain, the type, the number and the mixture of glycolether groups—PEG and/or PPG—and the ethoxylate chains. The retardation on SPE materials applied for extraction and/or concentration also depends on these properties and can therefore be used for an appropriate pre-separation of non-ionic surfactants in complex environmental samples as well as in industrial blends and household detergent formulations. A sequential selective elution from SPE cartridges using solvents or their mixtures can improve this preseparation and saves time in the later LC separation [22],... [Pg.259]

A much more demanding task is the analysis of fractions from liquid chromatography, not only with respect to molar mass but also with respect to chemical structure. The separation of a technical fatty alcohol ethoxylate (FAE) by liquid chromatography under conditions where the chain length as well as the end groups direct the separation is presented in Fig. 36. Using this chromatographic technique, the FAE was separated into three main fractions, the first fraction ap-... [Pg.51]

Foaming properties of alcohol ethoxylates and alcohol ethoxylate derivatives are related to chemical structure features such as hydrophobe size and linearity, ethylene oxide chain length, and the terminating group at the end of the ethylene oxide chain. Foaming properties may be mathematically related to chemical structure parameters using multiple correlation analysis. ... [Pg.203]

The high mass resolution that can be obtained by delayed extraction MAEDI-TOF has permitted the characterization of two poly(ethylene glycol) derivatives of pharmaceutical significance, PEG-bis(ephedrine) and PEG-bis(acefaminophenone). MALDI analysis confirmed that these polymers have ephedrine or acetaminophenone linked at both ends. End-group characterization, by MALDI-TOF, of derivatized and underivatized samples of octylphenol-teminated PEG revealed that the addition of carboxylic ends substantially enhances the detectability of these ethoxylated polymers. ... [Pg.469]

Among different nonionic surfactant classes, alkyl-phenol ethoxylates (APEOs) comprise the class meriting special attention with respect to environmental issues. The analysis of underivatized alkylphenolic compounds by GC-MS is restricted to the most volatile degradation products, such as alkylphenols and APEOs with less then 4-ethoxy groups. To overcome the problem of volatility, different offline and online derivatization protocols have been developed. Two complementary MS techniques, one using El and another using the less commonly used positive (P)CI, have been evaluated for the analysis of APEOs, their acidic (APECs) and neutral metabolites (APs), and halogenated derivatives. [Pg.2922]

The determination of alkyl chain distribution of alcohol ether sulfates can be most easily performed by gas chromatography after cleavage of the sulfated ethoxy moiety with hydri-odic acid. This procedure is similar to that described under the analysis of ethoxylated nonionic surfactants. The alkyl iodides from cleavage may also be determined by HPLC (72). An alternative approach requires the decomposition of the sulfate and ethoxy groups with the mixed anhydrides of paratoluenesulfonic and acetic acid, followed by GC determination of the alcohol acetates (73). [Pg.28]

This analysis is normally performed by HPLC (see Chapter 7) or, after hydrolysis of the sulfate group, by GC. Wet chemical methodology may also be applied if the sulfate groups are hydrolyzed, the determination of unethoxylated material can be performed in the same way as for alcohol ethoxylates. Hydrolysis conditions must be mild to avoid rupture of ether linkages. [Pg.29]

This method is optimized to determine the length of the poly(ethylene oxide) chain in, for example, an ethoxylated alcohol surfactant (11,12). It is also applicable to determination of oxypropylene content and to analysis of other products, such as EO/PO block copolymers (13,14). Quantitative results are not obtained from analysis of alkoxylated amines due to incomplete cleavage of the ethoxy group adjacent to the nitrogen. [Pg.67]

A particular problem with use of silica-supported reversed-phase media for trace analysis of surfactants is the presence of free Si-OH groups. These bind surfactants tightly, making complete recovery difficult, particularly for cationics (55). Phenyl-modified silica is excellent for SPE of NPE, but recoveries are low for AE, particularly more highly ethoxylated AE (55). [Pg.162]

Higher ethoxylated amines tend to be unstable at the temperatures required for GC analysis. For the analysis of ethoxylated amines of low degree of ethoxylation, which may contain residual active hydrogen, a drop or two of chlorotrimethylsilane is added to the / (trimethylsilyOacetamide reagent to replace any amine hydrogen with the trimethylsilyl group (41). [Pg.321]


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See also in sourсe #XX -- [ Pg.163 ]




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Ethoxylated

Ethoxylates

Ethoxylation

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